This invention is founded in the field of rotation sensors as typified by devices applying vibrating mechanical elements (vibratory elements) as the rotation indication means. Numerous base forms of vibratory elements used in such vibratory rotation sensors are known including disks, tuning forks, cylinders and hemispherical shells. All such vibratory rotation sensors exploit the effects of the Coriolis force produced by the rotation of its vibratory element(s). The Coriolis force is well known to detectably influence the orientation of a resonant vibratory pattern (standing wave) in a vibratory element in proportional accordance with the rotation of the element but independent of the rate of rotation.
Perhaps the most widely known form of vibratory rotation sensors employs three hemispherical shells as vibratory elements to detect rotation about three mutually orthogonal axes. Known in commercial avionics as Hemispherical Resonator Gyros (HRG), these devices provide a very high degree of accuracy and sensitivity at low rotation rates as required by inertial grade navigation systems. Other features of HRG include longer useful operating life, higher reliability and a more cost effective system than many alternative rotation sensing technologies for commercial and military aviation.
Other vibratory rotation sensors are intended mainly for tactical weapons guidance and control. Performance of this grade of sensor must withstand large linear and rotational accelerations characteristic of munitions. These types of sensors are more compact and less costly than HRG but are less accurate and sensitive at low rotation rates.
What are financially and functionally attractive rotation sensing packages in navigational avionics or weapons guidance are not so in other areas, for example commercial automotive electronics. Cost alone, aside from other factors such as size, mass and functional excesses or deficiencies would prohibit incorporation of such a device in an automobile for rotation sensing. A desirable automotive package would have a moderate degree of accuracy, rotation detection about a single axis, minimal size and mass, efficient design for mass manufacturing and cost commensurate with an automobile's overall price structure. Non-exhaustive exemplary system usages include vehicle navigation systems and chassis control systems such as active suspensions and active rear steering.